Killer instinct was a hard game, The second game I beat was the original Donkey Kong for the GameBoy. I beat the game then left my Gameboy in the car for a week during a Texas summer. Long story short, my Gameboy melted

If rolling the game over (eg. completing all the levels then staring back at level 1, which btw a lot of older games were like) counted, then there were like 4 arcade sytle space shooters like Galaxian that I beat 20 years ago on Vic 20 and commodores. I still chuckle when I think about those huge cartridges.

It would have to be Kirby, Super Mario Bros. 3, or Mortal Kombat. I remember beating those when I was young, I just don't remember which came first. It would probably have to be Kirby or Mario becuase I never played NES after we got.............................SEGA CHANNEL!!!!!!!!!